1. Field of the Invention
The invention relates to an actuating mechanism for the automatic operation of a gear-shift in a transmission.
2. Description of the Related Art
Actuating mechanisms for the automatic operation of gear-change in a transmission that allow different driving gears to be selected in any desired sequence are known for example from German reference DE 197 06 214 A1. These prior art actuating mechanisms comprise a first drive for driving a selector shaft in the axial direction and a second drive for driving the selector shaft in rotary fashion. One of these two movement types corresponds to shift path selection and the other to gear selection. The association of the drives to the movement type is specific to the particular transmission. A disadvantage of this type of prior art actuating devices for the automatic operation of speed-change transmissions is that when the desired gearshift procedure involves shift path selection such, for example, as shifting from second gear to third gear in an H-shaped shifting gate, it is necessary to activate a first drive to disengage the current gear and to then slow down again to assume the neutral position. When the neutral position is reached, the second drive is activated to change the shift path position. When the desired shift path position is reached, the first drive is again activated to engage the desired driving gear. The first drive for gear selection must be powerful enough to provide the force required for synchronization. Such drives have large inertial masses, which must be accelerated or retarded during every activation or braking of the engine, resulting in reaction inertia. The large inertial mass of the first drive causes a gearshift duration experienced as disruptive by the driver when the change in gear involves a shift path selection, due to the interruption in tractive force during the gearshift procedure.
Further, the automatic operation of a gear-change in a transmission by a gear-change cylinder drivable by an associated drive is known, for example, from German reference DE 197 13 423 A1. When this prior art type of actuating device is used, the individual driving gears are activated by the gear-change cylinder in a predetermined sequence only. If the driver wishes to skip one or more driving gears, the intervening gears must nonetheless be engaged at least briefly to allow the desired gear to be engaged. As a result, greater stress is placed on the synchronization devices. Moreover, the requirement to pass through the intervening gears lengthens the time to required to implement the desired change in gear.